Trigger and sear mechanism for machine-guns



E. FOWLER.

Tmasea AND SEAYR'MECHANISM FOR mcmms' suns. I APPLICAUON FIILED DEC. 6, l91 8- 1,375,451 'Patented' Apr. 19, 1921,

3 SHEETS-S HEET 1.

avwewtoz E. FOWLER. TRIGGER ANDSEAR MECHANISM FOR MACHINE GUNS.

' APPLICATION FILED DEC 6, I9I8. 11,375,45 1

Patented Apr. 19,1921.

3 SHEETS-SHEET 2.

Q RN E. FOWLER. TRIGGER AND SEAR MECHANISM FOR MACHINEGUNS.

7 APPLICATION FILED DEC. 6| 1918. 1,375,451, Patented Apr. 19,1921

3 SHEETS-SHEET 3- 1 ides, generally.

1 from engagement with men STATES ELBERT FOWLER, OF THE UNITED STATES ARMY.

TRIGGER AND SEAR MECHANISM FOR MACHINE- GUNS.

Specification of Letters Patent.

PatentedApr. 12, 1921.

Application filed December 6, 1918. Serial No. 265,609. (FILED UNDER THE ACT OF MARCH 3,1883, 22 STAT. L, 625.)

the United States, without payment of any royalty thereon;

The object of my invention is to provide a novel form of trigger and sear mechanism for machine guns, which is of maximum simplicity of construction and extremely sensitive and reliable in operation, and which is not. likely to getout of order. v

.VVith this object in view, the invention reand broadly s'tated, in the combination, with a sear, operably engageable with the firing-pin, of a trigger-controlled cam-member for releasing said sear the firing pin. The invention resides, more specifically stated in a verticallyrpositio'ned and vertically-movable scar, and a horizontally-rectilinearly movable, trigger-controlled cammember for actuatingsaid sear to firingpin releasing position. x The invention also resides in various improvements in structural parts going to make up the ultimate perfection of the gun, as an entirety.

The accompanying drawings 1 disclose an exemplary embodiment of the underlying principles of my invention. Like reference characters denote corresponding parts throughout the several views,fwhich latter may be briefly described as follows:

Figure l is a view in side elevation, partly in section,of a machine gun embodying my improved trigger and sear mechanism;

Figs. 2 and 3 are'cross sectionalviews on the lines 2-2 and 3+3, respectively, Fig. 1;

, longitudinal sec- Y tional view of a match e gun equippedwith Fig. 41 IS a fragmentary my improvements,

Fig. 5 is a detail perspec'z'tive view of the sear removed from the gun.

showing therelative po- 1 sition of the parts after the firing-pin has been released; I

. Fig. '6. is a detailperspective view of the trigger removed from the. gun;

Fig. 7 is a detail perspective View of the cam member removed from" the gun;

F gs. 8 and 9 are detail perspective views looking at the back and front, respectively, of the rear end plate of the gun, removed therefrom; i

Fig. 10 is a detail perspective view of the connection between the trigger and the cam member; and

Fig. 11 is a detail perspective view of the Referring now in detail to 1 designates the rear end plate of the gun,

which plate is provided with side ribs or splines 2, 2 which slide in corresponding grooves in the side plates 3, 3 of the gun.

The plate at its upper end is provided with a rearward-projecting, hollow head 4, having, on its uppersurface, lateral, forwardprojecting tongues .5, 5 bent at theirfree ends, as shown, to form downward-projecting terminalsfi, 6, which, in the assembled position of the parts, bear. uponthe upper surface of the top plate 7, as shown in- Figs. 1 and 1. g

The head 4: is provided with bearings 8, S, for the reception of a trigger-pivot 9, which passes through thehublO of the trigger 11,

the latter being provided with a finger 12 at its rear end.

Thetrigger is in the form of a bell-crank lever having the lever arm 18 engageable with an opening 1 1, in a plate 15, constituting a link or connection between the lever arm 13 and acam member 16 (more particularly hereinafter to be described). The link 15-is horizontally disposedwithin the hollow head 4; is adapted for limited rectilinear movement; and is supported, at its forward end, upon the upper surface of the top plate 7. Bearing against 15, is a bowed leaf -spring 16, which is prefe'rably secured to the link by a pin passing throughv a transverse hole 17, intermediate the endsiof said spring. The sprmg bears,

the rear end of said link the drawings.

at its ends, upon the inner surface of the vertical wall of the hollow head 4c. Above and below the hole 17, the spring carries forward-projecting lugs 23, 23, constltuting a support for the rear end of the link 15,

which is seated therebetween, as SllOWIllIl Figs. 1, and 4. The spring is for the purpose of returning the trigger 11, the link.

The cam member is provided, on its upper surface, with lateral, upstanding lugs 20, 20 provided, at their ends, with bent, forwardly-projecting terminals 21, 21, which enter a recess 22, 22 in the'li'nk 15 and bear against the front and rear walls of such recess. The terminals 21, 21 slide upon the upper surface of the top plate, 7, thereby supporting the cam-member at its rear end. The cam member 16 is bifurcated, as shown at 24, to provide legs 25, 25, having, at their free ends, downwardly-extending cam-portions 26, 26 having the downwardlyand forwardly inclined rear faces 27, 27, bearing upon the correspondingly-inclined upper surfaces of the inclined wing 28, at the upper end of the sear 29. The inclined faces 27, 27, may be formed'on side flanges on the 7 legs 25 opposite the flanges 18, 18.- The cam member may conveniently be formed of sheetmetal, bent or stamped to the desired form. The sear 29 is a vertically disposed mem her, having splines 30, 30, 'slidable in corresponding grooves 31, 31 in the breech-bolt 32. The sear is provided with the locking recess 34, in its upper surface, engageable with a projection 35 in the end surface of the firing-pin 36. i

The scar is also provided with a recess 37 in its front face, in which engages one end of a leaf spring 38', which is bifurcated to straddle the cocking-lever 38, and which is secured at its opposite end to the breech bolt 32, as by a pin 39, ,which projects through a recess 40 in the firing-pin. The spring 38 is operable to return the sear '29 to normal position, after depression thereof by the cam member 16.

By the construction and arrangement of the parts, as described, it will be noted that a horizontally rectilinear movement of the cam-member 16 effects a vertical movement of the sear 29.

The firing-pin cocking lever 38 is pivoted, at 41, to the breech bolt 32 and, at its lower end, projects into the recess 40 in said firing pin and, at its upper end, into a slot 42in the top plate 7 of the breech-casing. The upper end of the lever, in the cooked position of the firing-pin, is in proximity to the rear inclined face 43 of the slot 42, and to the inclined face 44 beneath the face '43. The slot 42 hasja front wall 45 inclinedoppositely to thewall 44.

As the breech bolt 32 moves from'thepositiO t eof s own in igs. 1 and 4, to its retracted positiomthe upper end of the cocking lever 38 strikes the inclined rear wall 43, which, in the continued rearward movement of the breech-bolt, causes the lever to turn upward and forward, until the upper end thereof escapes from the slot 42 in the top plate 7. This movement of the lever will breech-bolt, strikes against the inclined wall 45, and is thereby rocked to the position thereof shown in Fig. 1, so that, as the breech bolt reaches the firing position, the lower end of the lever is withdrawn from engagement with the rear wall of the slot 40, as shown in Fig. 1, leaving the firing-pin free to move forward, when the trigger 11 is depressed.

It is though that the operation of the sear and trigger mechanism is apparent from the "foregoing detailed description of the construction and relative arrangement of the. parts; but, briefly described, it is as follows:

The normal position of the parts, when the firing-pin is cooked and the breech-bolt U is in its forward-firing position, is as indicated in Fig. 1." In firlng the gun, the trigger 11 is depressed, by pressing upon the finger piece 12. This throws the lever arm '13 rearward, moving with it the link 15, which, in turn, pulls the cam-member 16 rearward.

The down-turnedend portions 26, 26 of the cam-member will thereupon force the sear 29 downward (from the'positionthereof shown in Fig. 1 to the position thereof shown in Fig. 4), since the inclined cam faces 27, 27 of said end portions bear against the correspondingly-inclined face of the wing 28 of the sear. This-downward movementof the sear moves the locking recess 34 out of engagementwith the projection 35 of the firing-pin 36,; whereupon said firingpin, under the impetus of the driving spring 46, drives the'firing-pin forward sufficiently to transmit the 'ignitingblow to the primer of the cartridge, in front of the breech bolt 32. V r

If the trigger 11 is immediately released, after movement thereof, the spring 16' returns the trigger,the link 15 and the cam member 16 to the-normal position thereof shown in Fig. 1, and the sear spring 38 returns the sear 29 to its upper position.

tion, what I claim as new and desire to secure by Letters Patent is:

-1. In a machine gun, a sear, a sear-actuating cam-member, comprising a plate bifurcated to form legs, the ends of which bear upon said sear, a trigger, and a connection between said cam-member and said trigger.

2. In a machine gun, a sear, a sear-actuating cam-member, comprising a plate bifurcated to form legs, the ends of which are downwardly inclined and bear upon said sear, a trigger, and a connection between said cam-member and said trigger.

3. In a machine gun having a top plate, a sear, a sear-actuating cam-member having upstanding lugs bent at their upper ends to form forwardly -projecting terminals bearing upon the top plate, a trigger, and a connection between said trigger and said cam-member and having recesses with which said terminals engage. I

4. In a machine gun having a rear end plate, a scar, a sear-actuating cam-member, a trigger carried by said end plate, a connection between said trigger and said cammem'ber and a bowed leaf spring between said end plate and said connection, and having projections, between which said connection is seated and by which it is supported.

ELBERT FOWLER. 

